The invention relates to a method of and machinery for making window envelopes and the like, provided with window patches of variously regulated dimensions and produced at high speeds of production. In this field much difficulty has been encountered because of the relative smallness of the window patches in comparison with typical envelopes, the innumerable variations of relative dimensions, the necessity to transfer and apply the cut window patches at great and increasing speeds, and the further necessity not to lose the advantage of a nominal patch applying speed by time consuming operations for readjustment of the machinery, mainly in cases of variation of relative dimensions of patches and envelopes.
The invention is an improvement on U.S. Pat. No. 3,618,483 of the present assignee, and on earlier patents listed therein.
The method of the invention is distinguished by providing a novel combination of modes and relative velocities of motion for the surfaces of a patch web, a cut-off patch, a patch transfer system, and an envelope blank. Details of these modes and velocities of motion will be described in connection with the operation of machines in accordance with the invention.
The invention provides two types of new apparatus, both for performance of the new method. The first new apparatus is distinguished by providing means whereby the newly cut-off patch first slips on a patch transfer cylinder or roll which rotates at envelope surface speed, while the patch is accelerated to the speed of the envelope, and whereby, mainly in a subsequent phase of its transfer, the cut-off patch is held against a transfer surface by a release segment. In certain forms of the first apparatus according to the invention, the release segment is located in a position close to the point of meeting between a patch transfer roll and the web transfer roll, for handling smaller patches. In another embodiment, the release segment is located adjacent the cutter roll and co-acts therewith.
The second and preferred new apparatus dispenses with the release segment and uses a novel combination of patch cutting means, transfer means and patch applying means.
This new combination is characterized by its ability to run a transfer cylinder at the exact surface speed of the envelop web, and to allow an edge of the patch to slide on this cylinder until the patch has been cut off, when the patch immediately assumes the surface speed of the transfer cylinder, equal to the envelope speed.